BBT charting query

Lisa • Married 5 years to a wonderful man. Son born 26 Jan 15. Expecting another boy in Nov 16 X
Hi ladies
​According to FF, I O on CD15. Whilst I think the cover line is a bit high, my post O temps have never been this low or taken a dip 2DPO. Least now at 3DPO they appear on the rise.
​But do you think the usually low temps or dip 2DPO is a bad sign? Do you think I definately ovulate?
​Thanks ladies